it's so subjective, it all depends on how one defines a "dimension" - is speed a dimension? mental strength? heart? fight? desire? attitude? Someone like Hewitt doesn't particularly have a "weapon" but he's hardly someone I'd consider "one-dimensional" - even Karlovic can serve AND volley. Is "dimension" synonymous with "weapon"?
Is there a truly one-dimensional player in the whole top 100? someone who really can only do ONE and ONLY one thing well? Is that the criteria? Or is it that they always play one style of game? Is gonzalez one-dimensional b/c all he does is hit the ball hard no matter what he's doing (serving, returning, rallying, etc) - but yet because he's got a good serve, returns well, and overall pretty good groundies, I'd never consider him "one-dimensional" even though he has one style of play and only one.
So in conclusion I think it's entirely subjective.. people who just need to put down a player b/c they don't like him will just slap on a "one-dimensional" label on him so they don't have to actually say anything intelligent
And they will give it a bad connontation, but no I do not think it's necessarily a bad thing.